In general, a blood circuit applied to a dialysis apparatus uses flexible tubes for passing blood of a patient therethrough, physiological saline or medicines to be dosed therethrough and connecting various medical instruments such as a dialyzer, chambers etc. A clamp device of the prior art generally comprises one branch formed with a first projection, the other branch formed with a second projection arranged oppositely to the first projection, an intermediate part connecting the one branch and the other branch each other, and an engaging part formed on the other branch of the clamp device adapted to engage the one branch of the clamp device as disclosed in Patent Document 1 below.
According to the clamp device of the prior art, it is possible to clamp the flexible tube and block flow of fluid flowing therethrough at the clamped position by elastically bending an intermediate part of the clamp device and engaging the one branch of the clamp device with the engaging part of the other branch of the clamp device to clamp the flexible tube laid between the first projection and the second projection of the clamp device. In addition, the clamp device of the prior art is provided with a guide part for guiding the one branch to the engaging part of the other branch to keep the clamping workability and prevent lateral displacement of the one branch of the clamp device during clamping work.
Patent Document 1: JP 2001-353215 A
However, although the clamp device of the prior art described above can prevent the lateral displacement of the one branch of the clamp device during clamping work, it does not have any effective mechanism for preventing the longitudinal displacement of the flexible tube during clamping work. Accordingly, it is afraid that the flexible tube would be clamped at a position in which the first projection and the second projection are longitudinally displaced when the first projection and the second projection are not exactly designed with respect to the longitudinal direction of the flexible tube and thus leakage of fluid would be caused. For surely performing the clamping of the flexible tube even at the longitudinally displaced position of the first and second projections, it is necessary to enlarge opposite areas (“sealing area”) of the first and second projections. However, it is afraid the enlargement of sealing area would make the clamping force excessive and accordingly a large force would be required when releasing the clamp of the flexible tube by disengaging the one branch from the engaging part and this would worsen the workability.
It is, therefore, an object of the present invention to provide a clamp device for a flexible tube which can minimize the sealing area and also prevent leakage of fluid as well as achieve easy release of the clamp device of a flexible tube.